Rotary dial





The rotary dial is a device mounted on or in a telephone or switchboard that
is designed to send interrupted electrical pulses, known as pulse dialing,
corresponding to the number dialed.

The dial is circular, about four inches (10 cm) in diameter, with 10
fingerholes cut through the outer perimeter. The dial is mounted via a shaft
extending from inside the phone or mounting and sits approximately 1/4 inch
(0.7 cm) above a faceplate. The faceplate is set so that through each
fingerhole letters and numbers printed on the faceplate may be seen. In the
US, traditional dials have letter codes displayed with the numbers under the
fingerholes in the following pattern: 1, 2 ABC, 3 DEF, 4 GHI, 5 JKL, 6 MNO,
7 PRS, 8 TUV, 9 WXY and 0 Operator. However, such letter codes were not used
in all countries (Older Australian rotary dial phones had them, but the
letter combinations were often printed in the centre plate adjacent to the
number). The 1 is normally set at approximately 60 degrees clockwise from
the uppermost point of the dial (if one imagines a clock face over the dial,
the 1 is located at approximately the 2 o'clock position), and then the
numbers progress upward counterclockwise, with the 0 being at about 5
o'clock. A curved device called a fingerstop sits above the dial at the 4
o'clock position. To dial a 6, the user puts a finger in the 6 fingerhole
and rotate the dial clockwise until it reaches the fingerstop. The user then
pulls out the finger, and a spring in the dial returns it to the resting
position. As the dial returns, electrical contacts wired through the
mechanism underneath will open and close 6 times, thus sending 6 pulses to
the receiving end. A centrifugal governor regulates the speed at which the
dial returns under the force of the spring.

You can fake out a phone system into thinking you are dialing a phone number
without ever turning a dial or pressing buttons. This method will fool the
system into thinking you are using a rotary phone. To do this, first find
the little button, switch, or hook that is pushed down when you hang up the
phone. To "dial" the digit 1, tap it once. For the digit 2, tap it twice
QUICKLY. For the digit 3, use three taps, etc. The digit 0 is ten taps.

Different pulse systems are used depending on which country you are in.
Sweden uses 1 pulse to signal the number zero, and 10 pulses to signal the
number nine. New Zealand uses ten pulses minus the number desired; so to
dial 7, the hook must be pressed three times. For this reason, the numbers
on the dial are shifted in different countries to work with their system.

Nowadays, not all phone systems and phones support this method.